1. Technical Field
The present invention relates to a microphone assembly detachably attached to a digital camera.
2. Description of the Related Art
Recently, a digital camera capable of capturing not only a still image but also a moving image for a longer period of time has been widely spread. The digital camera includes a camera body and a lens device fixed to or detachably attached to a front side of the camera body. The camera body is provided with an imaging device including an image sensor, an image processing device, an image recording device, and the like.
In high-grade cameras such as a single-lens reflex camera and a mirror-less camera, a detachable zoom lens is used as the lens device in many cases. The zoom lens is configured such that a focus lens is caused to move in an optical axis direction at the time of focusing and a magnification lens is caused to move in the optical axis direction at the time of zooming. Additionally, in many cases, the zoom lens has a shake correction device. In the shake correction device, in accordance with movement of a camera, a correction lens or an image sensor is caused to move in a direction opposite to a direction in which the camera moves, so as to prevent occurrence of image blur. A separate motor is used for each of the zooming operation, the focusing operation, and the shake correction. These motors are contained in the camera body or the lens device.
In the digital camera capable of capturing a moving image, a plurality of small sound collection holes are formed on the camera body. A built-in piezoelectric microphone having a simple structure, for example, is disposed behind the sound collection holes. Upon receiving instructions for recording sound, the built-in microphone converts the sound into a sound signal, and the sound signal is recorded together with image data of the moving image on a recording medium such as a memory card.
Since the motor for focusing, the motor for zooming, and the motor for image correction are driven during capturing of the moving image, the operating noise generated in the camera body is picked up by the built-in microphone. Additionally, since minute vibration due to the operation of the zoom motor and the like is transmitted to the built-in microphone, vibrating sound of the built-in microphone is also generated. As a result, continuous rasping noise is also recorded, and therefore it becomes impossible to perform recording with high-quality sound.
In order to prevent degradation in sound quality caused by operation of the lens device, a microphone assembly which is disposed outside the camera body and has a vibration isolation structure has been proposed. For example, according to Japanese Utility Model Registration No. 2530604, a microphone assembly includes a microphone unit having microphones contained in a metal casing and a base plate fixed to a rear end thereof, and an accordion elastic member disposed outside the microphone unit. The elastic member is inserted into an opening formed on the camera body of a digital camera (camera-integrated videotape recorder), and attached to a fixed wall of the camera body through a ring. The accordion elastic member functions so as not to transmit the operating noise of the lens device to the microphone unit.
According to Japanese Utility Model Registration No. 2530604, it is necessary to support the microphone unit at two points or support the microphone unit in a range having a certain degree of length by the accordion elastic member for the purpose of decreasing the vibration of the microphone unit. Accordingly, there arises a problem that the size of the microphone assembly is increased. As a countermeasure against this problem, it may be possible to provide an attachment shaft protruding downward from the casing of the microphone unit and support an outer circumference of the attachment shaft by a damper. In this case, although the vibration of the microphone unit in a planar direction can be absorbed by the damper, the vibration of the microphone unit in a vertical direction cannot be absorbed sufficiently by the damper. Further, according to Japanese Utility Model Registration No. 2530604, the microphone assembly is not detachable from the camera body, and therefore the microphone assembly disturbs a user when a moving image with sound is not captured.